Login allowlist bypass via empty post_password
Published Aug 6, 2026 · Updated Aug 6, 2026
Access-control bypass in SiteGround Security Optimizer 1.5.8 through 1.6.4 allows remote attackers to reach the WordPress login form. The Login Access request path treats an empty post_password field as a reason to skip the configured IP allowlist and returns the form instead of HTTP 403. The feature must be enabled and the source IP excluded; the bypass defeats network gating but does not bypass WordPress credentials.
Summary
What happened
Access-control bypass in SiteGround Security Optimizer 1.5.8 through 1.6.4 allows remote attackers to reach the WordPress login form. The Login Access request path treats an empty post_password field as a reason to skip the configured IP allowlist and returns the form instead of HTTP 403. The feature must be enabled and the source IP excluded; the bypass defeats network gating but does not bypass WordPress credentials.
The record
- CVE
- CVE-2026-13342
- Published
- Aug 6, 2026
- Updated
- Aug 6, 2026
- Vendor
- SiteGround
- Product
- Security Optimizer
- Classifications
- CWE-693, T1190
- Attack vector
- network
- Privileges
- unauthenticated
Timeline
How it unfolded
- Aug 6, 2026CVE publishedPublication date reported by the CVE source.
- Aug 6, 2026Record updatedLatest update available in the CVE record.
Exploitability
Present is not the same as exploitable
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Is a vulnerable build present?
Compare these published version ranges with your installed build and any vendor patches.
- Affected versionversion=1.5.8 <1.6.5
What conditions does exploitation require?
What is affected?
Published CVSS scores
CVSS describes severity. EPSS estimates exploitation probability.
Attacks
What attackers are doing with it
Daily unique IPs observed by Shadowserver honeypots for known exploited vulnerabilities (KEVs). Missing observations do not establish an absence of attacks.
Weakness, pattern, technique
Public exploit references
- WPScan post_password allowlist-bypass proof of conceptfunctional · validated
Labels summarize the accepted research assessment. They do not indicate a test against your environment.
Technologies
Your stack
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Your stack
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